Expandable Intervertebral Implant Screw Actuation
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Solution Overview
Problem
Current spinal stabilization methods lack an adjustable intervertebral implant that can effectively provide continuous expansion and retraction to accommodate varying anatomical needs and restore disc space height while minimizing tissue disruption during insertion.
Innovation Solution
An adjustable intervertebral implant with endplates having ramped surfaces and a sliding frame mechanism, actuated by a rotatable screw, allowing for controlled expansion and contraction to separate vertebrae, featuring a blocking mechanism to prevent screw backout and a polymeric material to prevent unintended rotation, enabling minimally invasive insertion and customizable fit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a traditional fixed-height intervertebral implant is used, then the implantation procedure is simple, but the implant cannot accommodate varying anatomical needs and cannot restore optimal disc space height
Solution Approach 1:
The implant transitions from a fixed structure to a dynamic adjustable structure through a screw mechanism that allows the endplates to move relative to each other along the longitudinal axis, enabling continuous height adjustment to accommodate varying anatomical needs while maintaining spinal stability
Solution Approach 2:
The implant is divided into separable components including endplates, a frame structure, and an adjustable mechanism with screw and nut elements, allowing independent optimization of each component's function while providing overall adaptability through their coordinated interaction
2Ease of operation
If a fixed-height implant is used, then the device structure is simple, but the implant cannot provide continuous expansion and retraction for precise vertebral positioning
Solution Approach 1:
The adjustable mechanism with screw and nut allows continuous dynamic adjustment of the distance between endplates along the longitudinal axis, enabling precise control over vertebral distraction and repositioning while maintaining a relatively compact structure
Solution Approach 2:
The implant enables continuous change of the height parameter (distance between endplates) through rotational adjustment of the screw mechanism, providing precise control over intervertebral space restoration without requiring multiple different implant sizes
3Object-affected harmful factors
If a minimally invasive insertion approach is used, then tissue disruption is reduced, but the implant requires adjustable height to accommodate limited insertion space
Solution Approach 1:
The implant can be inserted in a compressed state through minimally invasive approaches with reduced tissue disruption, then expanded in situ using the screw mechanism to achieve the desired final height and restore disc space without requiring large insertion corridors
Solution Approach 2:
The adjustment mechanism operates along the longitudinal axis (height dimension) independently from the insertion approach, allowing the implant to be inserted through a minimally invasive lateral or anterior approach while the height adjustment occurs along a different dimension after implantation
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The implant provides continuous expansion and retraction, allowing for precise distraction and repositioning of vertebrae, reduces tissue disruption during insertion, and offers a customizable fit to restore disc space height and maintain spinal stability.
Implementation Method 1
an actuator screw rotatably connected to the frame; and a carriage (a) forming an open area aligned with the openings in the first and second endplates and defining thereby a proximal carriage side and a distal carriage side with respect to the longitudinal axis, (b) threadably connected to the actuator screw, whereby rotation of the actuator screw moves the carriage with respect to the frame and the first and second endplates
Implementation Method 2
at least one ramped surface on a side opposite a bone engaging side; (c) including a plurality of ramps each mateable with at least one of the at least one ramped surfaces of the first and second endplates, wherein when the carriage is moved by rotation of the actuator screw, at least one of the at least one ramped surface of the first endplate and at least one of the at least one ramped surface of the second endplate each slide along at least one of the plurality of ramps of the carriage to cause the endplates to move relative to each other
Implementation Method 3
the implant further includes a polymeric material configured to press against the actuator screw to reduce a potential for unintended rotation of the actuator screw
Data Source
AI summary
An implant for therapeutically separating bones of a joint has two endplates each having an opening through the endplate, and at least one ramped surface on a side opposite a bone engaging side. A frame is slideably connected to the endplates to enable the endplates to move relative to each other at an angle with respect to the longitudinal axis of the implant, in sliding connection with the frame. An actuator screw is rotatably connected to the frame. A carriage forms an open area aligned with the openings in the endplates. The openings in the endplates pass through the carriage to form an unimpeded passage from bone to bone of the joint. The carriage has ramps which mate with the ramped surfaces of the endplates, wherein when the carriage is moved by rotation of the actuator screw, the endplates move closer or farther apart.